Refrigeration units for storing items such as meat and frozen foods over long periods of time are an essential component of contemporary life. Refrigeration units have widespread applicability and are found in such places as: refrigerators, coolers, ice cream boxes and freezers used for storing domestic family food items; ice cream and frozen food coolers and freezers in grocery stores; freezers and walk-in coolers for storage of the many food items used by public restaurants, school cafeterias and workplace cafeterias, and fast food stores; ice makers in restaurants and hotels for continuously supplying ice to patrons and guests; upright freezers and coolers in hospitals and veterinary clinics for storing medicine and blood at precise temperatures; refrigeration rooms in slaughterhouses; and computer operation rooms for cooling and dissipating the heat produced by mainframe computers.
In the above applications, as well as many others, the various items must be maintained within the refrigeration unit at below freezing temperatures for considerable lengths of time. Should the refrigeration unit fail, and the failure remain undetected, the items stored therein will degrade and spoil and have to be thrown out. The hardship this works not just for commercial and industrial enterprises, but for ordinary homeowners could be considerable. For example, an elderly couple on a fixed income would store the bounty of a summer season in their freezer for use throughout the winter only to lose that surplus bounty because the freezer broke down unbeknownst to them; and upon discover of the break down, the items stored within would have long since spoiled and must therefore be discarded nullifying the patient work and preparation of many months. Another example of the considerable loss that would occur would be the case of a single parent having purchased a large quantity of meat and produce for storage and use as needed throughout the winter, only to lose those stored items upon a freezer failure that remains undiscovered for many days.
Compounding the problem that refrigeration units often fail is the fact that many refrigeration units are located in basements, garages, or other out of the way places that are infrequently visited and inspected. As a result, the refrigeration unit may fail, and the failure may not become known for days, weeks or even months thereafter; and thus the ability of the refrigeration unit to maintain freezing conditions within the freezer cavity for the general 24 hour period after the initial failure is of only marginal value. While some refrigeration units do include warning or alarm lights, the lights are often too small to be noticeable unless they are viewed up close.
The prior art discloses a number of alarm devices and systems for freezing units to meet and overcome the above problems relating to refrigeration unit failure.
Thus, the Boyd device (U.S. Pat. No. 4,144,532) discloses a food freezer alarm that includes a sealed container mountable within the freezer compartment wherein a phase change of material within the container, resulting from a temperature increase, causes a conductive member to engage contacts that close a switch and set off an alarm warning the owner of undesirably high temperatures within the compartment.
The Kelley patent (U.S. Pat. No. 4,169,357) discloses a refrigerator-monitoring device that includes a temperature sensitive switch that closes when the temperature rises above a preset level thereby actuating a visible alarm and an audible alarm.
The Prosky patent (U.S. Pat. No. 4,283,921) discloses a freezer case alarm system that includes a sensing element operatively connected to a microcomputer so that the freezer compartment can be monitored, and if the temperature exceeds a certain limit, a first and a second alarm condition are energized.
The Hallett et al. patent (U.S. Pat. No. 4,855,721) discloses a freezer alarm apparatus that includes a sensor mounted within the freezer compartment that communicates with an externally mounted control unit for actuating a LED when the temperature within the compartment exceeds a preset temperature.
The Vidaillac patent (U.S. Pat. No. 6,034,607) discloses an electronic temperature alarm system that monitors ambient freezer temperature by a thermoresistor and in which a sound alarm is triggered by a piezoelectric buzzer when the freezer temperature exceeds a predetermined value.
Nonetheless, the remains a need for a freezer alarm system that is easy to install and provides clear and distinct signaling, in several forms, for remedial action and problem correction when the freezer unit temperature has exceeded a predetermined value.